The instantaneous center of velocity of two links that form a turning pair is located at（）
A. The center of the turning pair
B. On the circle of the turning pair
C. Any point on the circle of the turning pair
D. One of the two links
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Lower pairs are kinematic pairs with（）
A. No contact
B. Point contact
C. Line contact
D. Surface contact
The characteristics of Assur groups are（）
A. DOF=0
Basic link groups whose DOF=0 and cannot be further separated
C. Mechanical systems with lower pairs
D. Immobile mechanical systems with DOF=0
According to the types of contact, kinematic pairs can be classified into lower pairs and higher pairs. A higher pair refers to（）
A. Kinematic pair with point contact
B. Kinematic pair with line contact
C. Kinematic pair with surface contact
D. Kinematic pair with body contact
What are the main features of machines（）
Assembly of man-made components
B. Determinate relative motions among different components
Can conduct work/energy conversion
D. Well designed shapes and structures
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